BACKGROUND: Emerging data suggest increased arterial thrombosis risk in the months preceding a cancer diagnosis.

OBJECTIVES: To assess whether patients without documented vascular risk factors or pre-existing cardiovascular disease have a higher relative risk of cancer 12 months after arterial thrombotic events (ATE), compared to unselected patients.

PATIENTS/METHODS: A population-based cohort study of Clalit Health Services (CHS) database included CHS members ≥25 years without prior cancer or ATE (n = 2 804 584). An iterative matching process selected 10 potential controls chronologically for each consecutive exposed, age- and sex-matched (actual controls drawn 1:1 from a lot). Study exposure, ATE, was defined as ischemic stroke, transient ischemic attack, myocardial infarction or systemic arterial thromboembolism during hospitalization. The outcome was newly-diagnosed cancer within 12 months, based on Israeli national cancer registry. Cox proportional hazards multivariate regression calculated hazard ratio (HR) for outcomes, adjusted for cancer risk factors. Analysis also performed for three subgroups: age ≤50 years; no cardiovascular risk factors; no prior cardiovascular disease.

RESULTS: The full ATE and matched control cohorts included 43 108 patients. The 12-month cumulative incidence of cancer (95% confidence interval) was 0.020 (0.019-0.022) in the ATE cohort and 0.012 (0.011-0.013) in controls, corresponding to an adjusted HR of 1.665 (1.489-1.862). The relative risk of cancer was high in all subgroups up to a HR of 3.754 (1.912-7.372) in patients without cardiovascular risk factors.

CONCLUSION: There is an increased risk of previously undiagnosed cancer at 12 months after ATE, especially in patients without documented vascular risk factors or pre-existent cardiovascular disease.